Observation of a Distinct Transition in the Mode of Interconversion of Ring Pucker Conformers in Non-Crystalline D-Ribose-2'-d from H-2 NMR Spin-Alignment

Journal Article · Tue Jul 01 04:00:00 EDT 2003 · Journal of Biomolecular NMR, 26(3):249-257

DOI:https://doi.org/10.1023/A:1023899100654· OSTI ID:15003805

Liwang, Andy C ^[1]; McCready, David E ^[2]; Drobny, Gary P ^[3]; Reid, Brian R ^[4]; Kennedy, Michael A ^[2]

---

1. Texas A&
2. BATTELLE (PACIFIC NW LAB)
3. University of Washington
4. Washington University

Internal motions of D-ribose selectively 2H-labeled at the 2 position were measured using solid state 2H NMR experiments. A sample of D-ribose-2-d was prepared in a hydrated, non-crystalline amorphous state in an effort to reduce effects of crystal-packing. Between temperatures of -60 and -74?C the C2?H2 bond was observed to undergo two kinds of motions which were similar to those of C2?H2/H2 found previously in crystalline deoxythymidine (Hiyama et al. (1989) J. Am. Chem. Soc., 111, 8609-8613): (1) nanosecond motion of small angular displacement with an apparent activation energy of 3.6? 0.7 kcal/mol, and (2) millisecond to microsecond motion of large amplitude with an apparent activation energy≥4 kcal/mol. At -74?C, the slow, large-amplitude motion was best characterized as a two-site jump with a correlation time on the millisecond time scale, whereas at -60?C it was diffusive on the microsecond time scale. The slow, large-amplitude motions of the C2?H2 bond are most likely from interconversions between C2-endo and C3-endo by way of the O4-endo conformation, whereas the fast, small-amplitude motions are probably librations of the C2?H2 bond within the C2-endo and C3-endo potential energy minima.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 15003805
• Report Number(s): PNNL-SA-37177; KP1101010
• Journal Information: Journal of Biomolecular NMR, 26(3):249-257, Journal Name: Journal of Biomolecular NMR, 26(3):249-257 Journal Issue: 3 Vol. 26; ISSN 1573-5001; ISSN 0925-2738
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ACTIVATION ENERGY
AMORPHOUS STATE
PHASE TRANSFORMATIONS
POTENTIAL ENERGY
RIBOSE
SAMPLE PREPARATION